The solar-driven splitting of hydrohalic acids (HX) is an important and fast growing research direction for H₂ production. In addition to the hydrogen, the resulting chemicals (X₂/X₃−) can be used to propagate a continuous process in a closed cycle and are themselves useful products. Here we present a strategy for photocatalytic hydrogen iodide (HI) splitting using methylammonium lead iodide (MAPbI₃) in an effort to develop a cost-effective and easily scalable process. Considering that MAPbI₃ is a water-soluble ionic compound, we exploit the dynamic equilibrium of the dissolution and precipitation of MAPbI₃ in saturated aqueous solutions. The I^- and H⁺ concentrations of the aqueous solution are determined to be the critical parameters for the stabilization of the tetragonal MAPbI₃ phase. Stable and efficient H₂ production under visible light irradiation was demonstrated. The solar HI splitting efficiency of MAPbI₃ was 0.81% when using Pt as a cocatalyst.

Nature Energy 2, Article number: 16185 (2016)
doi:10.1038/nenergy.2016.185

http://www.nature.com/articles/nenergy2016185